go to white wolf airsmithing www.whitewolfairsmithing.com he has a drawing that gives you all the cuts and dimensions you need to do the halfblock then i would order halfblock bolt slep pin and hammer from jcurt not wwa ive had good luck getting parts from him but others never got what they ordered so your risk to order from wwa but good quality if you got the parts.. but the drawing on their site is a how to guide should work for you did for me..